Passive mechanical gravity compensation for robot manipulators

A simple mechanical method for passively compensating for gravitationally induced joint torques is presented. This energy-conservative gravity-compensation method is suitable for a variety of manipulator designs. With cables and appropriate pulley profiles, changes in potential energy associated with link motion through a gravity field can be mapped to changes in strain energy storage in spring elements. The resulting system requires significant energy input only for acceleration and deceleration or to resist external forces. A testbed with both single- and double-link configurations has demonstrated the efficiency and accuracy of this gravity compensation method, as well as its robustness under dynamic loading conditions.>